1. Technical Field
The present subject matter relates to a method for warning in case of wrong-way travel of a vehicle on a directional carriageway by means of an on-board unit carried by the vehicle, said on-board unit determining its position and direction of movement in a satellite-assisted manner, comparing the latter with a target direction of movement stored in a digital road map for this position and outputting a warning message when detecting a wrong-way travel. The present subject matter also relates to an on-board unit for such a method.
2. Background Art
On directional carriageways, for example motorways, highways, or dual directional carriageways, serious accidents occur as a result of wrong-way travel, since vehicles travelling the wrong way are not perceived in good time by other road users due to the high differences in speed, often insufficient ranges of vision and/or a lack of attention and preparation on the part of said other road users. In order to prevent accidents of this type, infrastructure measures have been taken previously, which are intended to prevent erroneous driving of a vehicle against the directional carriageway direction, for example physical separation of the joining and leaving slip roads, particular markings or warning signs, or warning messages in the case of detection of a vehicle travelling in the wrong direction, for example output via radio. However, these measures are incomplete, since they do not reach all road users.
Current satellite-assisted systems for position detection (global navigation satellite systems, GNSS) have sufficiently high accuracy for position detection that is accurate at lane level and can also determine the direction of movement. Compared with a digital road map, which is likewise accurate at lane level and which has stored a target direction of movement for each lane or position on the directional carriageway, an automatic detection and consequently also an automatic warning in the case of wrong-way travel of a vehicle is therefore possible, as is described for example in document WO 2012/120224 A1.
With the high spread of existing vehicles with on-board navigation systems or road toll on-board units with satellite-assisted position determination and an output unit for example for warning messages, a broad use of such a warning system in the case of wrong-way travel is possible. However, the usability of the warning system is limited by a lack of up-to-dateness of the map material used in the on-board unit and the high cost associated with the distribution (in particular the comprehensive distribution) of up-to-date maps; it is thus inflexible with regard to changes, thus resulting in errors in the detection and inaccurate warning messages.